In 1859, Edwin Drake brought in the world's first oil-producing well in Titusville, Pa. Ever since, we've used his discovery for almost everything imaginable --notably in and for our automobiles. These days, we find traces of Drake's discovery on the garage floor. Some are red, some green, while yet others are dark and greasy or clear and thin. We know something's leaking, but what is it that's leaking and what does it mean? Here's how to use yesterday's news for a do-it-yourself auto diagnosis. Before you pull into the garage, cover the floor with newspaper. the next morning, after you back out, check the spots. Dark greasy droplets indicate an oil leak. Clear oily stains might be brake fluids. Red drips are probably transmission fluid, and greenish puddles are anti-freeze in the coolant. Check the overnight drips for volume and color. And that's the On The House tip for today.